Make English the source language of the interface text

Every tr() source string in the code and the forms is now the English
text, and French is a translation (qet_fr.ts) like the other languages.
Generated, not hand-edited: master ef795a21e5 converted by
qet-en-source (harness 4c4ddc9).

3144 messages get an English source, 665 already had one, 0 left French; 8 shared-wording pairs disambiguated.
C++: 2904 literals in 233 files. Forms: 809 strings in 65 files. All 34 .ts files re-keyed; qet_fr.ts filled.
lupdate check: PASS. What each of 38 languages shows, old vs new: same 118266, English instead of French 38433, comment fallback 51, differences 0.

sources/ElementsCollection/ui/renamedialog.cpp

@@ -30,7 +30,7 @@ RenameDialog::RenameDialog(QString path, QWidget *parent) :
 	QET::trackDialogGeometry(this);
 	m_name = m_path.split("/").last();
 	if (m_name.endsWith(".elmt")) m_name.remove(".elmt");
-	ui->m_label->setText(tr("L'élément « %1 » existe déjà. Que souhaitez-vous faire ?").arg(m_path));
+	ui->m_label->setText(tr("The element « %1 » already exists. What do you wish to do?").arg(m_path));
 	ui->lineEdit->setText(m_name + QDate::currentDate().toString("dd-MM-yy"));
 }
 

sources/ElementsCollection/ui/renamedialog.ui

@@ -17,7 +17,7 @@
    <item row="1" column="0">
     <widget class="QLabel" name="label_2">
      <property name="text">
-      <string>Nouveau nom :</string>
+      <string>new name :</string>
      </property>
      <property name="alignment">
       <set>Qt::AlignCenter</set>
@@ -27,21 +27,21 @@
    <item row="2" column="0">
     <widget class="QPushButton" name="m_erase_pb">
      <property name="text">
-      <string>Écraser</string>
+      <string>Erase</string>
      </property>
     </widget>
    </item>
    <item row="2" column="1">
     <widget class="QPushButton" name="m_rename_pb">
      <property name="text">
-      <string>Renommer</string>
+      <string>Rename</string>
      </property>
     </widget>
    </item>
    <item row="2" column="2">
     <widget class="QPushButton" name="m_cancel_pb">
      <property name="text">
-      <string>Annuler</string>
+      <string>Undo</string>
      </property>
     </widget>
    </item>